1. Field of the Invention
The present invention relates to a vacuum cleaner and, more particularly, to a vacuum cleaner belt tensioner that provides constant belt tension with an increasing force on the belt as the belt lengthens with wear.
2. Description of the Prior Art
Known vacuum cleaners include a beater brush coupled by a belt to a beater brush drive motor that imparts rotation to the beater brush. As the belt wears, it lengthens and becomes less effective in coupling the beater brush to the drive motor. In order to maintain the coupling between the beater brush and the drive motor, known vacuum cleaners typically include a device for tensioning the belt. However, such known belt tensioners are somewhat inadequate in that the tension in the belt produced by such devices typically varies as the belt slackens or lengthens with wear. Low belt tension often decreases the life of the belt and high belt tension decreases the life of the bearings in the motor and beater brush dowel. It is important to the life of these parts that a minimum tension be maintained in the belt and that the maximum tension in the belt be limited.